Concrete Footing Calculator
Calculate concrete volume for strip footings, pad footings, pier footings and perimeter foundations. Get accurate quantities for your footing pour — residential slabs, post footings, retaining walls and commercial foundations.
🔨 Concrete Footing Calculator
📐 How It Works
Footing volume is calculated differently depending on footing type. Strip footings: Length × Width × Depth. Pad footings: Length × Width × Depth × Number of pads. Pier/round footings: π × radius² × depth × number of piers. Always add waste for form losses and ground irregularities.
📋 Worked Example
A house with 24m of strip footing, 450mm wide × 300mm deep: Volume = 24 × 0.45 × 0.30 = 3.24 m³. Plus 6 post pads 600×600×350mm: 0.6 × 0.6 × 0.35 × 6 = 0.756 m³. Total = 3.996 m³. With 10% waste = 4.4 m³. Order 4.5 m³ ready-mix.
❓ Frequently Asked Questions
Depth depends on soil conditions, frost depth and building loads. In Australia: residential strip footings typically 200–400mm deep. Post footings: 600–900mm depending on post height and soil. Always engage a structural engineer for engineered footing designs. Footings must be below unstable topsoil layers.
Residential footings: typically 20 MPa minimum (N20). Commercial or engineer-specified footings: 25–32 MPa. Check your engineer's specification or local building code. Never use premix bags for large structural pours — use ready-mix for consistency.
For residential footings, pouring in one continuous pour is preferred to avoid cold joints. If multiple pours are necessary, use a construction joint with exposed aggregate and a bonding agent. Never leave a cold joint in a critical structural location.
Concrete reaches approximately 70% of its design strength at 7 days and 95% at 28 days. For light timber frame construction, you can typically start building after 7 days. For heavy masonry or structural steel, wait the full 28 days unless the engineer specifies otherwise.